1. Field of the Invention
This invention relates to anti-mist compounds for printing inks and to the production of printing inks having inhibited misting tendencies when used on high speed printing presses.
2. Description of the Prior Art
The speed of printing presses has increased over the years such that web speeds exceeding 1200 feet per minute are common practice. Such high speeds have caused an increasing problem in the press room from ink which leaves the running presses in the form of a very fine spray or mist of ink which is thrown off by the fast moving rollers of the high speed press and which coats everything in the vicinity of the press with a sticky layer of ink.
Numerous efforts have been made to alleviate the misting problem and to provide printing inks which are capable of operation on high speed presses with little or no misting. Wolfe, Printing and Litho Inks, p. 270, 6th ed. (1967) states that ink flying or misting may be controlled in some measure by increasing the viscosity of the ink vehicle and by incorporating water and emulsifying agents in the ink to render it conducting. In addition, Wolfe suggests that by strongly ionizing the atmosphere in the vicinity of the rapidly revolving rollers the misting tendencies can be reduced. He acknowledges, however, that at very high press speeds even these measures are only partially successful. The addition of bentonite to printing ink as an anti-mist additive is suggested in U.S. Pat. Nos. 2,754,219 - Voet et al, 2,739,067 - Ratcliffe, 2,750,296 - Curado et al, and 2,766,127 - Voet. U.S. Pat. No. 3,015,632 - Remer suggests the incorporation of cationic amines or amides into ink to reduce the misting tendencies thereof.
U.S. Pat. No. 37,984 - Smillie discloses the use of a mixture of about 2 parts by weight of a powdered chromium compound and 1 part by weight of powdered asbestos to provide the basis for a green ink which is said to reduce the wear of plates or other printing surfaces on which green ink is commonly used. U.S. Pat. No. 1,553,914 - Rhodes describes the production of a paint or printer's ink solvent including the double silicate of magnesium and nickel. Neither the Smillie nor Rhodes patents are concerned with the problem of misting, however.
In general, the prior art attempts to solve the misting of inks have not been entirely successful since the anti-mist additives have been only partially effective and have generally resulted in a flatting and emulsification of the ink.